1/* $NetBSD: hash.h,v 1.5 2021/12/19 12:02:40 riastradh Exp $ */ 2 3/*- 4 * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Taylor R. Campbell. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#ifndef _LINUX_HASH_H_ 33#define _LINUX_HASH_H_ 34 35#include <sys/param.h> 36#include <machine/limits.h> 37 38static inline unsigned long 39hash_long(unsigned long value, unsigned int bits) 40{ 41 const unsigned long factor = (sizeof(factor) > 4? 42 0x9e37fffffffc0001ull : 0x9e370001ul); 43 44 return ((value * factor) >> ((CHAR_BIT * sizeof(value)) - bits)); 45} 46 47static inline uint32_t 48hash_32(uint32_t value, unsigned int bits) 49{ 50 return (value * 0x61c88647) >> (32 - bits); 51} 52 53static inline uint64_t 54hash_64(uint64_t value, unsigned int bits) 55{ 56 return (value * 0x61c8864680b583ebull) >> (64 - bits); 57} 58 59#endif /* _LINUX_HASH_H_ */ 60